Thursday, February 21, 2019

The North Atlantic Hurricane Season - June to November 2016

Reference: https://en.wikipedia.org/wiki/Timeline_of_the_2016_Atlantic_hurricane_season

STORM TYPES

Saffire Simpson Scale (for one minute maximum sustained winds)

Tropical Depression___________<= 62 km/hr
Tropical Storm_______________ 63 to 118 km/hr
Cat. One ___________________119 to 153 km/hr
Cat. Two ___________________154 to 177 km/hr
Cat. Three__________________178 to 208 km/hr
Cat. Four ___________________209 to 251 km/hr
Cat Five ____________________ >= 252 km/hr

This post only includes tropical depressions/storms that start in the Atlantic Ocean between the Equator and 23.5 degrees North. [Note Tropical Depression 9 - Hurricane Herman is included as it is a borderline case since it is first generated at 23.8 N]. The reason for excluding tropical depressions and tropical storms that start further than 23.5 degrees away from the equator is that their generation may have more to do with factors related to the mid-latitudes rather than the equatorial regions.

HYPOTHESIS TO BE TESTED

Tropical depressions or storms that appear in the Atlantic Ocean between the Equator and 23.5 degrees North during the 2016 North Atlantic Hurricane season, will do so on dates that are maxima or minima in the lunar-induced changes in the relative angular velocity of the Earth's rotation. [N.B. the dates that are maxima or minima in the lunar-induced changes in the relative angular velocity occur close to the times when the Moon crosses the Earth's equator or reaches lunar standstill (i.e. the Moon is furthest north or south of the Equator).]  

Summary of Results  (See the graphs below for confirmation)

Month__Tropical Depression/Storm_____Days from Peak Relative
____________________________________Angular Velocity

June_________Colin________________________ - 1.5 days
_____________Danielle_____________________ -0.5 days
August_______Earl________________________ + 2.0 days
_____________Fiona_________________________0.0 days
_____________Gaston______________________+ 1.5 days
_____________Hermine_____________________+2.0 days
September____Ian__________________________+1.5 days
_____________Karl_________________________-3.0 days
_____________Lisa_________________________+2.5 days
_____________Matthew______________________-0.5 days
October______Nicole________________________ -3.0 days
November____Otto__________________________-1.0 day
________________________________(rms)_____ 1.84 days

Note: The average spacing between maxima and minima is 6.83 days. However, it can be as high as 8-9 days and as low as 4-5 days. This means that if the starting dates of the tropical depressions and storms were randomly distributed, there should be as many storms at -3.0 (+/- 0.5) days as there are +1.0 (+/- 0.5) days. Clearly, much large sample sizes are needed before any definitive conclusions can be drawn. 

The table above shows that all of the tropical depressions/storms (with the possible exceptions of tropical depression Karl and tropical storm Nicole) appear to confirm our hypothesis that they first appear close to the dates on which the lunar-induced changes in the relative angular velocity of the Earth's rotation are either a maximum or minimum.

KEY FOR FIGURES

TD = Tropical Depression
TS = Tropical Storm
CATN = Category N Hurricane  where N = 1, 2, 3, 4, or 5.
PK = Peak Activity

**************
June 2016



Topical Depression 3 - Tropical Storm Colin

June 5th

12:00 UTC (21.6°N 88.0°W) – Tropical Depression Three develops from an area of low pressure approximately 130 km WNW of Cancún, Yucatán Peninsula.

18:00 UTC (22.4°N 87.9°W) – Tropical Depression Three intensifies into Tropical Storm Colin about 175 km NW of Cancún, Yucatán Peninsula.

June 7th 

00:00 UTC (29.4°N 84.3°W) – Tropical Storm Colin attains its peak intensity with maximum sustained winds of 85 km/h and a minimum barometric pressure of 1001 hPa roughly 110 km S of Tallahassee, Florida.

Topical Depression 4 - Tropical Storm Danielle

June 19th 

12:00 UTC (19.9°N 94.1°W) – Tropical Depression Four develops from an area of low pressure about (235 km) ENE of Heroica Veracruz, Mexico.

June 20th 
06:00 UTC 20.0°N 95.5°W) – Tropical Depression Four intensifies into Tropical Storm Danielle roughly 110 km NNE of Heroica Veracruz, Mexico.

12:00 UTC (20.7°N 96.1°W) Tropical Storm Danielle attains its peak intensity with maximum sustained winds of 75 km/h and a minimum barometric pressure of 1007 hPa approximately 155 km ESE of Tamiahua, Mexico.


****************

July 2016

There were no storms in July

****************

August 2016



Tropical Storm Fiona - Hurricane Earl
August 2nd
06:00 UTC (16.3°N 77.5°W) – Tropical Storm Earl develops from an area of low pressure about 185 km S of Jamaica.
August 3rd
18:00 UTC (16.9°N 85.4°W) – Tropical Storm Earl intensifies into a Category 1 hurricane roughly 265 km ESE of Turneffe Atoll, Belize.
    August 4th
    04:00 UTC (17.4°N 87.8°W) – Hurricane Earl attains its peak intensity with maximum sustained winds of 140 km/h and a minimum barometric pressure of 979 hPa as it crosses the coast of Belize.

    Tropical Depression 6 - Tropical Storm Fiona

    August 6th 

    18:00 UTC (12.0°N 32.2°W) – Tropical Depression Six develops from an area of low pressure approximately (1,150 km) west-southwest of the Cabo Verde Islands.

    August 17th 

    12:00 UTC (13.7°N 36.0°W) – Tropical Depression Six intensifies into Tropical Storm Fiona about 1,480 km W of the Cabo Verde Islands.

    August 19th

    00:00 UTC (16.9°N 41.5°W) – Tropical Storm Fiona attains its peak intensity with maximum sustained winds of 85 km/h and a minimum barometric pressure of 1004 hPa roughly 1,330 km ENE 
    of the Leeward Islands.

    Tropical Depression 7 - Tropical Storm Gaston - Hurricane Gaston

    August 22

    12:00 UTC  (11.5°N 26.5°W) – Tropical Depression Seven develops from an area of low pressure roughly 490 km SW of the southernmost Cabo Verde Islands.

    18:00 UTC (12.0°N 28.2°W) – Tropical Depression Seven intensifies into Tropical Storm Gaston approximately 500 km SW of the southernmost Cabo Verde Islands.

    August 24

    12:00 UTC (15.8°N 39.1°W) – Tropical Storm Gaston intensifies into a Category 1 hurricane about 1,555 km W of the Cabo Verde Islands.

    August 27

    18:00 UTC (28.7°N 53.6°W) – Tropical Storm Gaston re-intensifies into a Category 1 hurricane approximately 1,145 km SE of Bermuda.

    August 28th 

    12:00 UTC (30.3°N 54.7°W) – Hurricane Gaston intensifies into a Category 2 hurricane about 980 km ESE of Bermuda.

    18:00 UTC (30.5°N 55.0°W) – Hurricane Gaston intensifies into a Category 3 hurricane roughly 950 km ESE of Bermuda.

    Tropical Depression 9 - Tropical Storm Hermine - Hurricane Hermine

    August 28th 

    18:00 UTC (23.8°N 81.4°W) – Tropical Depression Nine develops from an area of low pressure about 95 km SSE of Key West, Florida.

    August 29th

    06:00 UTC (24.4°N 88.0°W) – Tropical Depression Nine intensifies into Tropical Storm Hermine about 385 km NNW of Cancún, Mexico.

    September 1st

    18:00 UTC 27.9°N 85.5°W – Tropical Storm Hermine intensifies into a Category 1 hurricane about 210 km SSW of Apalachicola, Florida.

    ***********************
    September 2016



    Tropical Storm Ian - Rapidly heads north and becomes a subtropical storm

    September 12th

    06:00 UTC  (20.5°N 49.3°W) – Tropical Storm Ian develops from an area of low pressure about 1,665 km SE of Bermuda.

    September 14th 

    18:00 UTC (32.1°N 53.8°W) – Tropical Storm Ian transitions into a subtropical storm about 970 km E of Bermuda.

    Tropical Depression 12 - Tropical Storm Karl

    September 14th

    06:00 UTC (16.2°N 23.2°W) – Tropical Depression Twelve develops from an area of low pressure while centered near the eastern Cabo Verde Islands.

    September 15th
    06:00 UTC (17.5°N 28.7°W) – Tropical Depression Twelve intensifies into Tropical Storm Karl about 360 km W of the Cabo Verde Islands.

    Tropical Depression 13 - Tropical Storm Lisa

    September 19th

    12:00 UTC (13.4°N 27.3°W) – Tropical Depression Thirteen develops from an area of low pressure about 360 km WSW of the southern Cabo Verde Islands.

    September 20th

    12:00 UTC (15.1°N 30.0°W) – Tropical Depression Thirteen intensifies into Tropical Storm Lisa about 570 km W of the southern Cabo Verde Islands.

    September 22nd

    12:00 UTC (19.7°N 33.8°W) – Tropical Storm Lisa attains its peak intensity with maximum sustained winds of 85 km/h and a minimum barometric pressure of 999 hPa about 940 km WNW of the Cabo Verde Islands.

    Tropical Storm Matthew - Hurricane Matthew

    September 28th

    12:00 UTC (13.4°N 59.8°W) – Tropical Storm Matthew develops from an area of low pressure about 25 km WNW of Barbados.

    September 29th

    18:00 UTC (14.2°N 66.9°W) – Tropical Storm Matthew intensifies into a Category 1 hurricane approximately 300 km NE of Curaçao.

    September 30th

    06:00 UTC (14.0°N 69.3°W) – Hurricane Matthew rapidly intensifies into a Category 2 hurricane about 185 km N of Curaçao.
    12:00 UTC (13.8°N 70.4°W) – Hurricane Matthew rapidly intensifies into a Category 3 hurricane about 145 km NNW of Aruba.
    18:00 UTC (13.5°N 71.2°W) – Hurricane Matthew rapidly intensifies into a Category 4 hurricane about 160 km NW of Aruba.

    October 1st

    00:00 UTC (13.4°N 71.9°W) – Hurricane Matthew rapidly intensifies into a Category 5 hurricane and simultaneously attains peak winds of 270 km/h about 215 km WNW of Aruba.

    ***********************
    October 2016



    Tropical Storm Nicole - Hurricane Nicole

    October 4th
    06:00 UTC (23.2°N 59.8°W) – Tropical Storm Nicole develops from an area of low pressure about 855 km NE of San Juan, Puerto Rico.

    October 6th

    18:00 UTC 27.3°N 65.1°W – Tropical Storm Nicole intensifies into a Category 1 hurricane about 555 km S of Bermuda.

    October 7th

    00:00 UTC (27.5°N 65.2°W) – Hurricane Nicole intensifies into a Category 2 hurricane about 530 km S of Bermuda. [Note that this is the peak intensity of Hurricane Nicole until it re-intensifies over October 11th, 12th, and 13th, peaking at category 4].

    ***********************
    November 2016


    Tropical Depression 16 - Tropical Storm Otto - Hurricane Otto

    November 20th

    18:00 UTC (11.1°N 79.7°W) – Tropical Depression Sixteen develops from an area of low pressure about 195 km N of Colón, Panama.

    November 21st

    06:00 UTC (11.3°N 79.3°W) – Tropical Depression Sixteen intensifies into Tropical Storm Otto roughly 235 km NNE of Colón, Panama.

    November 23rd

    18:00 UTC (11.2°N 81.1°W) – Tropical Storm Otto intensifies into a Category 1 hurricane approximately 250 km NW of Colón, Panama.

    November 24th

    06:00 UTC (11.1°N 82.4°W) – Hurricane Otto intensifies into a Category 2 hurricane about 150 km E of the Costa Rica–Nicaragua border.

    12:00 UTC (11.0°N 83.0°W) – Hurricane Otto intensifies into a Category 3 hurricane and simultaneously attains its peak intensity with maximum sustained winds of 185 km/h and a minimum barometric pressure of 975 hPa roughly 75 km E of the Costa Rica–Nicaragua border.

    Monday, February 18, 2019

    Friday, February 15, 2019

    The Lunar Smoking Gun


    Wilson and Sidorenkov, A Luni-Solar Connection to Weather and Climate I: Centennial Times Scales, J Earth Sci Clim Change 2018, 9:2 DOI: 10.4172/2157-7617.1000446

    https://www.omicsonline.org/open-access/a-lunisolar-connection-to-weather-and-climate-i-centennial-times-scales-2157-7617-1000446.pdf


    When a plot is made of the precision of these [lunar] alignments, in a frame-of-reference that is fixed with respect to the Perihelion of the Earth’s orbit, the most precise alignments take place in an orderly pattern that repeats itself once every 208.0 years: 

    0 × (28.75 + 31.00) + 28.75 years = 28.75 years ≈ 25.5 FMC’s 
    1 × (28.75 + 31.00) + 28.75 years = 88.5 years ≈ 78.5 FMC’s 
    2 × (28.75 + 31.00) + 28.75 years = 148.25 years ≈ 131.5 FMC’s 
    3 × (28.75 + 31.00) + 28.75 years = 208.0 years ≈ 184.5 FMC’s 

    A simple extension of this pattern gives additional precise alignments at periods of 236.75, 296.50, 356.25, 416.0, 444.75 and 504.5 years. The full significance of the 208-year repetition pattern in the periodicities of the lunar alignment index (ϕ) only becomes apparent when these periodicities are compared to those observed in the spectra for two proxy time series. 

    Abstract 

    Lunar ephemeris data is used to find the times when the Perigee of the lunar orbit points directly toward or away from the Sun, at times when the Earth is located at one of its solstices or equinoxes, for the period from 1993 to 2528 A.D. The precision of these lunar alignments is expressed in the form of a lunar alignment index (ϕ). When a plot is made of ϕ, in a frame-of-reference that is fixed with respect to the Perihelion of the Earth’s orbit, distinct periodicities are seen at 28.75, 31.0, 88.5 (Gleissberg Cycle), 148.25, and 208.0 years (de Vries Cycle). The full significance of the 208.0-year repetition pattern in ϕ only becomes apparent when these periodicities are compared to those observed in the spectra for two proxy time series. The first is the amplitude spectrum of the maximum daytime temperatures (Tm) on the Southern Colorado Plateau for the period from 266 BC to 1997 AD. The second is the Fourier spectrum of the solar modulation potential (ϕm) over the last 9400 years. A comparison between these three spectra shows that of the nine most prominent periods seen in ϕ, eight have matching peaks in the spectrum of ϕm, and seven have matching peaks in the spectrum of Tm. This strongly supports the contention that all three of these phenomena are related to one another. A heuristic Luni-Solar climate model is developed in order to explain the connections between ϕ, Tm and ϕm. 

    Monday, February 11, 2019

    The Lunar Tidal Model - Part 4


    Please read:

    The Lunar Tidal Model - Part 1
    http://astroclimateconnection.blogspot.com/2019/02/the-lunar-tidal-model-part-1.html

    The Lunar Tidal Model - Part 2
    https://astroclimateconnection.blogspot.com/2019/02/the-lunar-tidal-model-part-2.html



    The Lunar Tidal Model - Part 3
    http://astroclimateconnection.blogspot.com/2019/02/the-lunar-tidal-model-part-3.html

    Introduction

    An MJO is a complex atmospheric wave that moves from west-to-east along the equator. It is most evident when it couples with atmospheric convection/precipitation between East Africa and the equatorial Western Pacific Ocean. It consists of an active region of enhanced precipitation/uplift followed by a region of suppressed precipitation. The precipitation pattern takes about 30 – 60 days to complete one cycle when seen from a given point along the equator.

    The slow-moving MJO wave can be thought of as a combination of an easterly moving Kelvin-wave and a westerly moving equatorial Rossby wave. The compound MJO wave moves with a group velocity of about 5 m/sec from west-to-east. Within the large MJO wave train, Kelvin waves move from west-to-east with a phase velocity of 15 to 20 m/sec, and the equatorial Rossby Waves travel from east-to-west with a phase velocity of 5 m/sec.


    Figure 1


    Equatorial Rossby Waves (ERW)

    In parts 1, 2, and 3, it was shown that the westward-moving ERWs trailing the active phase of the MJO are being generated at the times when there is an ebb in the lunar-induced atmospheric/oceanic tides at the Earth's equator [when measured at the same time in the 24.8-hour lunar tidal day], i.e. either at a tidal minimum (at a lunar standstill) or at a tidal maximum at the Earth's equator (at a lunar equatorial crossing).

    Figure 2 reminds us that these ebbs in the lunar-induced atmospheric/oceanic tides at the Earth's equator occur roughly every 6-7 days, either when the peak of the Moon's tidal bulge crosses the Earth's equator (tidal maximum) or when it reaches its maximum distance from the Earth's equator i.e. lunar standstill (tidal minimum).


    Figure 2




    Equatorial Kelvin Waves (EKW)


    The MJO can be thought of as a combination of an easterly moving EKW and a westerly moving ERW with the compound MJO wave moving with a group velocity of about 5 m/sec from west-to-east. Within the larger MJO wave train, Kelvin waves move from west-to-east traveling through MJO with a phase velocity of 12 to 20 m/sec. Specifically, the phase velocity of an EKW is typically 15 — 20 m/sec (west-to-east) over the western Pacific Ocean and 12 — 15 m/sec (west-to-east) over the Indian Ocean. In addition, EKWs are non-dispersive waves, so their phase velocity is equal to their group velocity. Hence, their slower speed over the Indian Ocean is attributed to the fact that, in these regions, EKWs are coupled with the atmospheric convection and precipitation.

    See Dr. Kyle MacRitchie's excellent blog site for further details:

    If you were to observe the Moon from a fixed point on the Equator at the same time each day, you would notice that the sub-lunar point on the Earth's surface appears to move at a speed of 15 — 20 m/sec from west-to-east. This is the result of the fact that the west-to-east speed of the Moon along the Ecliptic (as seen from the Earth’s center) varies between 15.2 — 19.8 m/sec. 

    Interestingly, the west-to-east group (and phase) velocity for the convectively-decoupled EKW in the western Pacific Ocean is 15 — 20 m/sec, as well. This remarkable "coincidence" leads to a very intriguing hypothesis (N.B. the following assumes that the observer is at a fixed location on the Earth's equator). 

    Could it be that the easterly moving EKW that are embedded within the MJO wave complex is produced by the interaction between the day-to-day movement of the lunar-induced atmospheric/oceanic tides with a meteorological phenomenon that routinely occurs at roughly the same time each (24 hr) solar day? 

    THE FIRST POSSIBILITY

    The first meteorological phenomenon that comes to mind is the observation that in the tropics the peak in convective thunderstorm activity routinely takes place at roughly 3.00 p.m. each afternoon.

    Hypothesis: EKWs are generated when the peak in the lunar-induced tides passes through the local meridian at 3:00 p.m. local time* when the daily thunderstorm activity reaches its peak (this takes place roughly once every half synodic month = 14.8 days)**. In addition, if the generation of an EKW occurs at roughly the same time as the generation of an ERW (which takes place roughly once every quarter of a Tropical month = 6.83 days)***, the combined atmospheric waves reinforce the Westerly Wind Bursts (WWBs) that are produced by ERWs.

    Some important notes:

    * The lunar-induced tidal peak can pass through the local meridian (during its daily passage) both when the Moon is passing through the meridian and when the Moon is passing through the anti-meridian due to the semi-diurnal nature of the peak tides.

    ** If you select times when the Moon passes through the local meridian at a fixed time (e.g. 3:00 p.m.), you are in fact selecting times when the Moon is at a specific phase (or a fixed point in the Synodic month). Hence, when the Moon is passing through the meridian at 3:00 p.m. for someone located in the equatorial Indian and western Pacific Oceans, the Moon's phase is at ~15 % (Waxing Crescent), and when the Moon is passing through the local anti-meridian it's at ~85 % (Waning Gibbous).

    ***There are four times where the Moon either crosses the equator or reaches a standstill in one Tropical month.

    The main prediction of this hypothesis is that WWBs should be enhanced near the active phase of an MJO every time an ebb in the lunar-induced equatorial tides coincides with the time when the peaks in the semi-diurnal tides pass through the local meridian at 3:00 p.m.

    One way to test this prediction is to look at a Hovmoller diagram of Westerly Wind Burst anomalies (WWBanom). This should show that whenever there is a temporal alignment between the two generating mechanisms, there should be an increase in the WWBanom. 

    Figure 3 below shows the Hovmeller diagram of the WWBanom (between +/- 15 degrees latitude) versus geographic longitude between January 1st, 2002 and December 31st, 2003. The starting and ending dates were chosen to cover the 2002/2003 El Nino event, which spans the period from May 2002 and February 2003.

    Ref: Australian Bureau of Meteorology (BOM) - last accessed 12/02/2019.
    http://www.bom.gov.au/climate/mjo/#tabs=Time-longitude 

    The thick black horizontal lines that are superimposed on this plot show the 45 degrees East and 180 degrees East meridians. The former marks the western-most part of the Indian Ocean off the coast of East Africa and the later marks the location of the International Date-Line.

    Large crosses are superimposed on figure 3, using:

    a) the dates on which the peaks in the semi-diurnal tides pass through the local meridian at 3:00 p.m (which are assumed to be responsible for the EKWs), at the same time as there is an ebb in the lunar-induced equatorial tides (which are assumed to be responsible for the ERWs).    

    b) the longitude of the MJO phase for that date.

    [Note: the following table is used to convert between MJO phase and longitude: Phase 1 = 60 deg. E; Phase 2 = 75 deg. E; Phase 3 = 90 deg. E; Phase 4 = 105 deg. E; Phase 5 = 120 deg. E; Phase 6 = 150 deg. E; Phase 7 = 170 deg. E; Phase 8 arbitrarily set to 120 deg. W.]

    All of the points are plotted that have a difference between, the time when the peaks in the semi-diurnal tides pass through the local meridian at 3:00 p.m., and the time when there is an ebb in the lunar-induced equatorial tides, that is either -1, 0, or +1 days.    

    Figure 3



    Important Notes:

    1. The passage of MJO events across the Indian and Western Pacific oceans in figure 3 are traced out by positive (purple) WWB anomalies. Hence, simply plotting a point in figure 3, using its MJO phase and its date, will automatically place that point along one of the purple paths traced out by the MJO event. Hence, what we are looking for in figure 3 is not whether the alignment points lie along the paths traced out by the MJO but whether or not these points are near noticeably enhanced periods of WWB anomalies in a given MJO event.

    2. The points that have alignments of 0 or 1 days appear to lie in MJO phase regions 5, 6 or 8, at least over the one and half year period that is centered on the 2002/2003 El Nino event. 

    [Note: information from a much longer time series extending from January 1996 to January 2019 shows that points that are not aligned (i.e. not 0 or 1 days) are not preferentially clustered in MJO phase regions 5 and 6.] 

    3. The points that have alignments of 0 or 1 days and which are located in the MJO phase regions 5 and 6, appear to immediately precede noticeably enhanced periods of WWB anomalies by a couple of days. This appears to confirm the main prediction of our hypothesis.

    4. There appear to be noticeably enhanced periods of WWB anomalies in MJO phase regions 5 and 6 that lie halfway in between the points that have alignments of 0 or 1 day.

    Note 4. strongly suggests that our orginal hypothesis needs to be modified to allow for the possibility that the easterly moving EKW that are embedded within the MJO wave complex is produced by the interaction between the day-to-day movement of the lunar-induced atmospheric/oceanic tides with a meteorological phenomenon that not only occurs at around 3:00 p.m. local time but also 12 hours earlier around 3:00 a.m. local time.  

    A MORE LIKELY POSSIBILITY 

    One meteorological phenomenon that fits this bill is the atmospheric surface pressure variations measured at a given location in the tropics. At many points near the equator, the atmospheric surface pressure spends much of its time sinusoidally oscillating about its long-term mean with an amplitude of 1 to 2 hPa (or millibars). Generally, this regular daily oscillation is only disrupted by the passage of a tropical low-pressure cell.

    Figure 4 shows the diurnal surface pressure variations in the Carribean as measured by Haurwitz (1947). What this shows is that like many points near the Earth's equator, the atmospheric surface pressure in the Carribean reaches a minimum near 4:00 -- 4:30 a.m. and 4:00 -- 4:30 p.m.

    Figure 4.
    Source; Figure 1 of Haurwitz B., 1947, Harmonic Analysis of the Diurnal Variations of Pressure and Temperature Aloft in the Eastern Caribbean, Bulletin of the American Meteorological Society, Vol. 28, pp. 319-323.  
    This leads us to modify our original hypothesis so that it reads:

    Modified Hypothesis: 

    EKWs are generated when the peak in the lunar-induced tides passes through the local meridian at either 4:00 a.m. or 4:00 p.m. local time when the diurnal surface pressure is a minimum (this takes place roughly once every quarter of a synodic month = 7.38 days). In addition, if the generation of an EKW occurs at roughly the same time as the generation of an ERW (which takes place roughly once every quarter of a Tropical month = 6.83 days), the combined atmospheric waves reinforce the Westerly Wind Bursts (WWBs) that are produced by ERWs.

    Further research is being carried out to test this modified hypothesis.

    Thursday, February 7, 2019

    The Lunar Tidal Model - Part 3

    Please read:

    The Lunar Tidal Model - Part 1
    http://astroclimateconnection.blogspot.com/2019/02/the-lunar-tidal-model-part-1.html

    The Lunar Tidal Model - Part 2
    https://astroclimateconnection.blogspot.com/2019/02/the-lunar-tidal-model-part-2.html


    The following question was presented in Part 2:

    "Are the equatorial Rossby waves, that are seen trailing the active phase of an MJO, being generated at the times when there is an ebb in the lunar-induced atmospheric/oceanic tides at the Earth's equator [when measured at the same time in the 24.8-hour lunar tidal day], either at a tidal minimum (i.e. at a lunar standstill) or at a tidal maximum (i.e. at a lunar equatorial crossing)?"

    As a reminder, figure 1 [i.e. figure 2 in Part 2] below shows a schematic diagram of the relative (lunar-induced) tidal height on the Earth's equator, when measurements are taken at a fixed point in the 24.8-hour lunar tidal day. [Again, note that this is only a rough schematic diagram that is designed to give an idealistic view of how the tides would vary over a lunar tropical month. No attempt is made to allow for the varying distance of the Moon from the Earth and the actual values shown in the graph are only intended to create a qualitative impression of what is happening.]

    Figure 1 starts out with the sub-lunar point at its northernmost latitude and it shows that there are four times during a tropical month where there is an ebb in the equatorial tidal height [when measured at a fixed point in the lunar day]. Each one corresponds to a lunar equatorial crossing or a lunar standstill.


    Figure 1


    The following refers to a specific case of an MJO event that occurred just recently between December 2nd of 2018 and January 6th of 2019. Figure 2 below shows lunar-induced changes in the the relative angular velocity (Delta Omega/Omega) of the Earth over this time period [Sidorenkov 2009]. This figure is used to identify six dates during this MJO event that are at, or within one day of, one of the times of either a lunar equatorial crossing or a lunar standstill. These dates are close to times when there is an ebb in the lunar-induced atmospheric/oceanic tides at the Earth's equator [when measured at the same time in the 24.8-hour lunar tidal day].
      
    Figure 2

    The following set of six figures show surface wind patterns (1000 hPa level) in the Earth's atmosphere on the dates that are highlighted in figure 2 (https://earth.nullschool.net/). The wind maps cover the equatorial regions of the Indian and Western Pacific oceans. Each map shows the nominal location of the active phase of the MJO on the designated date [Note: This is only a rough estimate that is based upon the geological location of the published MJO phase for that date (Wheeler and Hendon 2004, BOM 2019)]. Additionally, each map shows the location of the Westerly Wind Bursts
    (WWBs) and Equatorial Rossby Waves (ERW) associated with each MJO event. All six maps show surface wind conditions for the geological location of the active phase of the MJO at a time that corresponds to the local mid-afternoon













    Some important points to note:

    a) The MJO event stalls in phase 5 (located just south of the Philippines) between the December 15th, 2018 and January 1st, 2019. This could indicate that the propagation of this MJO wave was impeded by:
    • its passage through the Maritime Province (i.e. the Indonesian Archipelago)
    • its temporary linkage to the monsoon trough across the northern part of Australia.
    b) The twin low-pressure cells that form on each side of the equator are a manifestation of the westerly propagating Equatorial Rossby Wave (ERW). These low-pressure cells only start forming a day or so before the dates of the six surface wind maps and so they appear to be associated with the ebb of the lunar-induced tides along the Earth's equator roughly once every 6.8 days.

    c) The reemergence of a strong MJO event in phase region 7, following its passage through the Maritime Province, could be the result of the decoupling between the slower moving MJO wave and a much faster move Kelvin Wave that usually takes place in this region of the western Pacific Ocean.

    Conclusion:

    Careful analysis of these six maps supports the contention that the equatorial Rossby waves, that are seen trailing the active phase of an MJO, are being generated at the times when there is an ebb in the lunar-induced atmospheric/oceanic tides at the Earth's equator [when measured at the same time in the 24.8-hour lunar tidal day], i.e. either at a tidal minimum (at a lunar standstill) or at a tidal maximum at the Earth's equator (at a lunar equatorial crossing).

    N.B. This blog post is not a definite proof of the stated conclusion, however, it does provide evidence for further investigation of the proposed hypothesis.   

    References:

    Sidorenkov, N.S., 2009: The Interaction Between Earth’s Rotation and Geophysical Processes, Weinheim: Wiley.

    https://earth.nullschool.net/ last accessed 07/02/2019

    Wheeler, M. C., and H. H. Hendon, 2004: An all-season real-time multivariate MJO index:
    Development of an index for monitoring and prediction. Mon. Wea. Rev.132, 1917-1932.

    Australian Bureau of Meteorology (BOM), 2019: http://www.bom.gov.au/climate/mjo/  last accessed 06/02/2019.